阻止惡意遠(yuǎn)程線程

阻止惡意遠(yuǎn)程線程在WIN2000/XP/2003里，遠(yuǎn)程線程只有在建立新進(jìn)程時(shí)，系統(tǒng)會(huì)用遠(yuǎn)程線程調(diào)用新進(jìn)程的入口函數(shù)，除此之外，建立遠(yuǎn)程線程的一般是惡意程序，如何發(fā)現(xiàn)這些惡意程序并找到建立惡意程序的執(zhí)行文件呢？下面本人提供一個(gè)最近完工的小程序。先說(shuō)原理：在WIN2000/XP/2003里，建立本地線程和遠(yuǎn)程線程都是調(diào)用ntdll.dll里的NtCreateThread函數(shù)，只不過(guò)是如果建立本地線程，則進(jìn)程句柄是-1，反之則是目標(biāo)進(jìn)程的句柄（一個(gè)大于0且小于0xffffffff的具體數(shù)字）。而本程序先駐留ntdll+800h處的空隙，之后攔截NtCreateThread，如果是建立本地線程則跳過(guò)，如果是建立遠(yuǎn)程線程，就跟蹤到目標(biāo)進(jìn)程，在目標(biāo)進(jìn)程分配4K內(nèi)存，把自身復(fù)制到目標(biāo)進(jìn)程，并且把遠(yuǎn)程線程的入口改為跟蹤代碼，經(jīng)過(guò)跟蹤代碼的判斷，而決定是否讓遠(yuǎn)程線程執(zhí)行。判斷規(guī)則是：如果遠(yuǎn)程線程所處的模塊沒(méi)有MZ頭和PE頭，則拒絕；如果遠(yuǎn)程線程的入口是LoadLibrary函數(shù)的地址，也拒絕；其他的就放行。由于要搶先攔截NtCreateThread函數(shù)，所以采用驅(qū)動(dòng)的形式。編譯方法：@ml/c/coff/Cp%1.asm@link/subsystem:native/driver:wdm/release/align:16/base:0x10000/section:.text,RWE/out:%1.sys%1.obj@del%1.obj安裝驅(qū)動(dòng)的方法：copy/yartwdm.sys%systemroot%/system32/driverssccreateartwdmbinpath=%systemroot%/system32/drivers/artwdm.systype=kernelerror=ignorestart=systemscstartartwdm下面是源代碼：.586p.modelflat,stdcalloptioncasemap:noneassumefs:nothingassumegs:nothingincludelibntoskrnl.lib;必須從WIN2000DDK復(fù)制到MASM的INCLUDE目錄NtQuerySystemInformationproto:dword,:dword,:dword,:dword.constalign4szdlldb'ntdll.dll',0align4szNtQueryVirtualMemorydb'NtQueryVirtualMemory',0align4szNtAllocateVirtualMemorydb'NtAllocateVirtualMemory',0align4szNtWriteVirtualMemorydb'NtWriteVirtualMemory',0align4szNtCreateThreaddb'NtCreateThread',0align4szMyLdrLoadDlldb'LdrLoadDll',0.data?dwTempVardd?szTempBufferdb10000hdup(?).codestart:;int3nopnopnopnoppushadcall_GetNtdllHandle;獲取ntdll.dll的地址movebx,eaxmovhntdll,eax.if!eaxjmp_exit.endifpushoffsetszMyLdrLoadDll;獲取ntdll.LdrLoadDll函數(shù)的地址pushebxcall_GetProcAddressmovlpLdrLoadDll,eax.if!eaxjmp_exit.endifpushoffsetszNtQueryVirtualMemory;獲取ntdll.NtQueryVirtualMemory函數(shù)的地址pushebxcall_GetProcAddressmovlpNtQueryVirtualMemory,eax.if!eaxjmp_exit.endifpushoffsetszNtAllocateVirtualMemory;獲取ntdll.NtAllocateVirtualMemory函數(shù)的地址pushebxcall_GetProcAddressmovlpNtAllocateVirtualMemory,eax.if!eaxjmp_exit.endifpushoffsetszNtWriteVirtualMemory;獲取ntdll.NtWriteVirtualMemory函數(shù)的地址pushebxcall_GetProcAddressmovlpNtWriteVirtualMemory,eax.if!eaxjmp_exit.endifpushoffsetszNtCreateThread;獲取ntdll.NtCreateThread函數(shù)的地址pushebxcall_GetProcAddressmovesi,eax.if!esijmp_exit.endifmovecx,cr0btcecx,16movcr0,ecxmovdwordptr[ebx+32h],'fgm'.ifbyteptr[esi+5]!=0bah;判斷ntdll.NtCreateThread函數(shù)的第二條指令是不是movedx,xxxxxxxx（指令長(zhǎng)度5字節(jié),以0bah開(kāi)頭,剛好替換成一條call指令）jmp_exit.endifaddesi,10;ESI指向被替換指令movedx,xxxxxxxx的尾部moveax,[esi-4];保存原來(lái)指令的操作數(shù)xxxxxxxxmovdwordptr_HookNtCreateThread+1,eaxleaedi,[ebx+800h];EDI指向駐留地址（ntdll.dll+800h）處moveax,edisubeax,esi;計(jì)算兩條指令的相對(duì)地址movdwordptr[esi-4],eax;修改NtCreateThread函數(shù)的第二條指令為call指令movbyteptr[esi-5],0e8h;修改NtCreateThread函數(shù)的第二條指令為call指令movesi,offset_HookNtCreateThreadmovecx,offset_AssertRemoteThreadEnd-offset_HookNtCreateThreadrepmovsb;攔截代碼駐留ntdll.dll+800hmovecx,cr0btsecx,16movcr0,ecx_exit:popadxoreax,eaxret8;以上代碼在驅(qū)動(dòng)入口執(zhí)行,權(quán)限為RING0_GetNtdllHandleproc;獲取ntdll.dll的地址之函數(shù)xoreax,eaxpushadinvokeNtQuerySystemInformation,11,offsetszTempBuffer,10000h,offsetdwTempVar.if!eaxmovedi,dwTempVaraddedi,offsetszTempBuffermovesi,offsetszdll.whiledwordptrszTempBufferpushfdpushesipushedicldxoreax,eaxsubedi,100hmovecx,30hrepnzscasbsubedi,10push10pushedicall_Mytolowermovecx,9repzcmpsbsetzalpopedipopesipopfd.ifalsubedi,11chmoveax,[edi+8]mov[esp+1ch],eax.break.endifsubedi,11chdecdwordptrszTempBuffer.endw.endifpopadret_GetNtdllHandleendp_MytolowerproclpName,dwSize;大寫(xiě)轉(zhuǎn)小寫(xiě)函數(shù)pushadmovesi,lpNamemovedi,esimovecx,dwSize.repeatlodsb.ifal>='A'&&al<='Z'addal,20h.endifstosb.untilcxzpopadret_Mytolowerendp;以下代碼在ntdll+800h處運(yùn)行,RING3_HookNtCreateThread:;攔截ntdll.NtCreateThread函數(shù)的代碼movedx,0enter400h,0pushfdpushad.ifdwordptr[ebp+0ch+0ch]==-1;如果在本地進(jìn)程建立線程就返回jmp_HookNtCreateThreadExit.endif;程序執(zhí)行到這里,表明有線程要在別的進(jìn)程建立遠(yuǎn)程線程,以下的代碼將跟蹤到目標(biāo)進(jìn)程并在目標(biāo)進(jìn)程做判斷db0e8h,2,0,0,0,'M','$'popedxsubedx,$-3movebx,edx;代碼重定位leaesi,_AssertRemoteThread[ebx]leaedi,[ebp-400h]movecx,offset_AssertRemoteThreadEnd-offset_AssertRemoteThreadrepmovsb;復(fù)制跟蹤代碼到局部緩沖區(qū),原因是當(dāng)前代碼處于ntdll+800h地址處,是只讀的,而后面的變量必須賦值,因此只有;把從標(biāo)簽_AssertRemoteThread開(kāi)始的代碼復(fù)制到可寫(xiě)的局部堆棧里的緩沖區(qū)leaedx,[ebp-8]leaecx,szwkernel32[ebx]movdwordptr[edx],001a0018hmovdwordptr[edx+4],ecx;構(gòu)造UNICODE_STRING的kernel32.dll字符串moveax,offsethKernel32-offset_AssertRemoteThread;計(jì)算hKernel32變量距離駐留代碼開(kāi)頭_AssertRemoteThread標(biāo)簽的偏移leaesi,[ebp-400h+eax]pushesipushedxleaeax,[ebp-0ch]pusheaxleaeax,szwEnvStr[ebx]pusheaxcalllpLdrLoadDll[ebx];裝載KERNEL32.DLL,如果失敗就返回,如果成功則kernel32的模塊地址存入hKernel32變量.ifeaxjmp_HookNtCreateThreadExit.endifleaedx,szGetProcAddress[ebx]pushedxpush[esi]call_GetProcAddress;獲取KERNEL32.GetProcAddress()的地址movecx,offsetlpGetProcAddress-offset_AssertRemoteThreadmov[ebp-400h+ecx],eax;放入局部緩沖區(qū)里的代碼中的lpGetProcAddress變量里movedi,eaxleaedx,szGetModuleFileName[ebx]pushedxpush[esi]calledi;獲取KERNEL32.GetModuleFileName()的地址movecx,offsetlpGetModuleFileName-offset_AssertRemoteThreadmov[ebp-400h+ecx],eax;放入局部緩沖區(qū)里的代碼中的lpGetModuleFileName變量里leaedx,szGetCurrentProcessId[ebx]pushedxpush[esi]calledi;獲取KERNEL32.GetCurrentProcessId()的地址calleax;獲取當(dāng)前進(jìn)程的PIDmovecx,offsetdwProcessId-offset_AssertRemoteThreadmov[ebp-400h+ecx],eax;PID放入局部緩沖區(qū)里的代碼中的dwProcessId變量里leaedx,szGetCurrentThreadId[ebx]pushedxpush[esi]calledi;獲取KERNEL32.GetCurrentThreadId()的地址calleax;獲取當(dāng)前線程的TIDmovecx,offsetdwThreadId-offset_AssertRemoteThreadmov[ebp-400h+ecx],eax;TID放入局部緩沖區(qū)里的代碼中的dwThreadId變量里movesi,[ebp+8];定位調(diào)用NtCreateThread()的代碼地址,放在ESI.ifesi>70000000hmovesi,[ebp]movesi,[esi+4];定位調(diào)用NtCreateThread()的代碼地址,放在ESI.endifleaedi,[ebp-20h]pushedipush20hpushedipush0pushesipush-1calllpNtQueryVirtualMemory[ebx];定位調(diào)用NtCreateThread()的代碼地址所處的模塊地址.if!eaxmoveax,[edi+4]subesi,eaxmovecx,offsetdwModuleRva-offset_AssertRemoteThreadmov[ebp-400h+ecx],esi;把調(diào)用NtCreateThread()的代碼地址所處的模塊RVA值放入dwModuleRva變量里movecx,offsetszModuleName-offset_AssertRemoteThreadleaedi,[ebp-400h+ecx]push78hpushedi;EDI指向局部緩沖區(qū)里的代碼當(dāng)中的szModuleName緩沖區(qū)pusheaxmovecx,offsetlpGetModuleFileName-offset_AssertRemoteThreadcalldwordptr[ebp-400h+ecx];把調(diào)用NtCreateThread()的代碼地址所處的模塊的模塊名放入szModuleName緩沖區(qū)里.endifleaesi,[ebp+0ch]moveax,[esi+14h]moveax,[eax+0b0h]movecx,offset_AssertRemoteThreadJmp-offset_AssertRemoteThread-5movdwordptr[ebp-400h+ecx],eax;替換遠(yuǎn)程線程的開(kāi)始地址,使其指向我的跟蹤代碼的地址leaecx,[ebp-4]leaedx,[ebp-8]movdwordptr[ecx],1000hmovdwordptr[edx],0push4push1000hpushecxpush0pushedxpushdwordptr[esi+0ch]calllpNtAllocateVirtualMemory[ebx];在目標(biāo)進(jìn)程分配4K內(nèi)存,把跟蹤代碼復(fù)制過(guò)去,目標(biāo)進(jìn)程就會(huì)先執(zhí)行跟蹤代碼,進(jìn)行判斷后再執(zhí)行遠(yuǎn)程線程.ifeaxjmp_HookNtCreateThreadExit.endifmovecx,offset_AssertRemoteThreadEnd-offset_AssertRemoteThreadleaedx,[ebp-400h]push0pushecxpushedxpushdwordptr[ebp-8]pushdwordptr[esi+0ch]calllpNtWriteVirtualMemory[ebx];復(fù)制跟蹤代碼.if!eaxmovedx,[ebp-8]moveax,[esi+14h]movdwordptr[eax+0b0h],edx;如果在目標(biāo)進(jìn)程分配內(nèi)存失敗就恢復(fù)原來(lái)的遠(yuǎn)程線程的開(kāi)始地址.endif_HookNtCreateThreadExit:popadpopfdleaveretlpNtAllocateVirtualMemorydd0lpNtWriteVirtualMemorydd0lpLdrLoadDlldd0_HookNtCreateThreadend:align4szwkernel32dw'k','e','r','n','e','l','3','2','.','d','l','l',0align4szwEnvStrdw'c',':','/','w','i','n','d','o','w','s',';','c',':','/','w','i','n','d','o','w','s','/','s','y','s','t','e','m','3','2',0_GetModuleAddress:@@:andax,0f000hsubeax,1000hcmpwordptr[eax],'ZM'jnz@bmovecx,eaxaddecx,[ecx+3ch]cmpdwordptr[ecx],'EP'jnz@bret_GetProcAddressprocusesecxesiedi,_hModule,_lpszProcNamelocal@dwSizemovedx,_hModuleaddedx,[edx+3ch]movedx,[edx+78h]addedx,_hModulemovecx,[edx+18h]movesi,[edx+20h]movedi,_lpszProcNamepushedipushecxxoreax,eaxmovecx,0ffffffffhrepnzscasbnotecxdececxmov@dwSize,ecxpopecxpopediaddesi,_hModule@@:pushedipushecxmovecx,@dwSizelodsdaddeax,_hModulexchgeax,esirepzcmpsbxchgeax,esipopecxpopediloopnz@b.if!ZERO?xoreax,eaxret.endifsubesi,_hModulesubesi,4subesi,[edx+20h]shresi,1addesi,[edx+24h]addesi,_hModulelodsdmovzxeax,axshleax,2addeax,[edx+1ch]addeax,_hModulemovedx,[eax]addedx,_hModulexchgedx,eaxret_GetProcAddressendpalign4_AssertRemoteThread:;本函數(shù)現(xiàn)在已經(jīng)處于遠(yuǎn)程線程所在的目標(biāo)進(jìn)程pushaddb0e8h,2,0,0,0,'M','$'popedxsubedx,$-3movebx,edxleaedi,_AssertRemoteThreadEnd[ebx]pushedipush20hpushedipush0push_AssertRemoteThreadJmp[ebx-5]push-1calllpNtQueryVirtualMemory[ebx];獲取原來(lái)遠(yuǎn)程線程分配的模塊地址.ifeaxpushebpleaeax,_AssertRemoteThreadSafe[ebx]pusheaxleaeax,_AssertRemoteThreadJmp[ebx]pusheaxpushfs:[0]movfs:[0],esp;設(shè)置SEHmoveax,_AssertRemoteThreadJmp[ebx-5]andeax,0fffff000h.repeatsubeax,1000h.untilwordptr[eax]=='ZM';循環(huán)查找遠(yuǎn)程線程代碼所處的模塊的MZ頭_AssertRemoteThreadSafe:popfs:[0]popecxpopecxpopecxmovedi,eax.elsemovedi,[edi+4].endif.ifwordptr[edi]!='ZM';如果沒(méi)有找到MZ頭,說(shuō)明遠(yuǎn)程線程是純代碼,絕大部分是含有惡意的,拒絕執(zhí)行jmp_AssertRemoteThreadDeny.endifaddedi,[edi+3ch].ifdwordptr[edi]!='EP';如果找的MZ頭,再找PE頭,如果找不到PE頭,,絕大部分是含有惡意的,拒絕執(zhí)行jmp_AssertRemoteThreadDeny.endifleaedx,szLoadLibraryA[ebx]pushedxpushhKernel32[ebx]calllpGetProcAddress[ebx].ifeax==_AssertRemoteThreadJmp[ebx-5];如果遠(yuǎn)程線程的開(kāi)始地址是LoadLibraryA函數(shù)的地址,也拒絕執(zhí)行jmp_AssertRemoteThreadDeny.endifleaedx,szLoadLibraryW[ebx]pushedxpushhKernel32[ebx]calllpGetProcAddress[ebx].ifeax!=_AssertRemoteThreadJmp[ebx-5];如果遠(yuǎn)程線程的開(kāi)始地址是LoadLibraryW函數(shù)的地址,也拒絕執(zhí)行jmp_AssertRemoteThreadExit.endif_AssertRemoteThreadDeny:;執(zhí)行到這里時(shí),遠(yuǎn)程線程已經(jīng)被拒絕執(zhí)行,這里負(fù)責(zé)顯示一個(gè)提醒對(duì)話(huà)框leaedx,szLoadLibraryA[ebx]pushedxpushhKernel32[ebx]calllpGetProcAddress[ebx];獲取LoadLibraryA的地址leaecx,szUser32[ebx]pushecxcalleax;裝載USER32.DLLmovhUser32[ebx],eaxleaedx,szMessageBox[ebx]pushedxpushhUser32[ebx]calllpGetProcAddress[ebx];獲取MessageBox函數(shù)的地址movesi,eaxleaedx,szwsprintf[ebx]pushedxpushhUser32[ebx]calllpGetProcAddress[ebx];獲取wsprintf函數(shù)的地址movedi,eaxleaedx,szGetCurrentProcessId[ebx]pushedxpushhKernel32[ebx]calllpGetProcAddress[ebx];獲取GetCurrentProcessId函數(shù)的地址calleax;GetCurrentProcessId()pusheaxmoveax,dwModuleRva[ebx]pusheaxmoveax,dwThreadId[ebx]pusheaxmoveax,dwProcessId[ebx]pusheaxleaeax,szModuleName[ebx]pusheaxleaeax,szformat[ebx]pusheaxleaeax,_AssertRemoteThreadEnd[ebx]pusheaxcalledi;格式化字符串a(chǎn)ddesp,4*7leaedx,sztitle[ebx]leaedi,_AssertRemoteThreadEnd[ebx]push34hpushedxpushedipush0callesi;顯示MESSAGEBOX.ifeax==6;如果用戶(hù)按了"確定"鍵,就終止建立遠(yuǎn)程線程的代碼所處在的線程leaedx,szNtOpenThread[ebx]pushedxpushhntdll[ebx]calllpGetProcAddress[ebx];獲取NtOpenThread函數(shù)的地址leaedx,dwProcessId[ebx]pushedxleaedx,stForOpenThread[ebx]pushedxpush1pushedicalleax;OPEN建立遠(yuǎn)程線程的線程.if!eaxleaedx,szNtTerminateThread[ebx]pushedxpushhntdll[ebx]calllpGetProcAddress[ebx];獲取NtTerminateThread函數(shù)的地址push0p